Artillery Wagon unlocked before Railway technology researched.

[GreyTheWolf]

Fairly self-descriptive: Artillery Wagons can be researched via the Artillery technology, which doesn't have the Railway technology as a prerequisite. This means that the player can craft a type of rail car before unlocking the technology needed to craft rail-related items in the first place, making a researched item completely unusable until the Railway technology has been researched.

[Rseding91]

Thanks for the report however that is intended. The research also unlocks the standalone turret.